In vivo Metastasis Assay

Female BABL/c nude mice (4–6 weeks old) were purchased from Shanghai SLAC Laboratory Animal Centre (Shanghai, China). For in vivo pulmonary metastasis assays, MKN-7 cells (1 × 10⁷) were transfected with agomir-NC (5 μM) or agomir-1224 (5 μM), respectively. The cells were injected into the lateral tail veins of each anesthetized nude mice (5 per group). Seven weeks after injection, the animals were killed, and lungs were embedded in paraffin and stained with HE for further pathological confirmation. The tumor metastasis nodules were obtained by the number of nodules on HE section with the aid of a dissecting microscope (OLYMPUS, Japan).